Wireless terminal, metering device, and communication control method

Abstract

A wireless terminal ( 12 ) includes a wireless transceiver ( 121 ) and a controller ( 122 ). The wireless transceiver ( 121 ) is configured to adjust, according to magnitude of a path cost to reach a gateway node ( 11 ) in a wireless multi-hop network ( 10 ) formed by communication of the wireless transceiver ( 121 ), a waiting time before joining the wireless multi-hop network ( 10 ) after power supply restoration. As a result, for example, it is possible to contribute to stable reconfiguration of a wireless multi-hop network.

1 . A wireless terminal comprising:
 a wireless transceiver configured to communicate with a node; and   a controller comprising at least one hardware processor and configured to adjust, according to magnitude of a path cost to reach a gateway node in a wireless multi-hop network formed by communication of the wireless transceiver, a waiting time before joining the wireless multi-hop network after power supply restoration.   
     
     
         2 . The wireless terminal according to  claim 1 , wherein the controller is adapted to increase the waiting time before joining the wireless multi-hop network in such a manner that the larger the path cost is, the more the waiting time is increased. 
     
     
         3 . The wireless terminal according to  claim 1 , further comprising a power supply circuit configured to supply electric power to the wireless transceiver and the controller, wherein
 the power supply restoration is a change to a state where the wireless transceiver and the controller can start their operations by the electric power supplied from the power supply circuit.   
     
     
         4 . The wireless terminal according to  claim 1 , wherein the controller is adapted to determine the waiting time by using the path cost that was stored at least a predetermined time before detection of a power failure in the wireless terminal. 
     
     
         5 . The wireless terminal according to  claim 1 , wherein the controller is adapted to detect a power failure by receiving a notification indicating an occurrence of a power failure from a node in the wireless multi-hop network. 
     
     
         6 . The wireless terminal according to  claim 1 , wherein the controller is adapted to determine the waiting time by using the path cost that was stored when a multi-hop path between the gateway and the wireless terminal had remained unchanged for at least a predetermined time. 
     
     
         7 . The wireless terminal according to  claim 1 , wherein the magnitude of the path cost includes a hop count to the gateway. 
     
     
         8 . The wireless terminal according to  claim 1 , wherein the path cost includes a Received Signal Strength Indicator. 
     
     
         9 . The wireless terminal according to  claim 1 , wherein the gateway relays data between the wireless multi-hop network and an external network. 
     
     
         10 . The wireless terminal according to  claim 1 , wherein
 the controller is adapted to adjust the waiting time by adjusting a start timing of a control procedure for joining the wireless multi-hop network, and   the control procedure includes at least one of a procedure for establishing an association with a node, an authentication procedure performed between the wireless terminal and the gateway, and a procedure for setting a multi-hop path between the gateway and the wireless terminal.   
     
     
         11 . The wireless terminal according to  claim 1 , wherein
 the wireless multi-hop network conforms to ZigBee, ZigBee PRO, or ZigBee IP,   the controller is adapted to adjust the waiting time by adjusting a start timing of a control procedure for joining the wireless multi-hop network, and   the control procedure includes at least one of (a) transmission of a Beacon Request message to an adjacent node in the wireless multi-hop network, (b) transmission of an Association Request message to the adjacent node, (c) transmission of an authentication request message to the gateway, (d) a procedure for obtaining an IP address, (e) transmission of a DODAG Information Solicitation message to the adjacent node, and (f) transmission of a DODAG Destination Advertisement Object message to the gateway.   
     
     
         12 . A metering device comprising:
 a wireless terminal according to  claim 1 ; and   a meter reading unit configured to collect meter reading data, wherein   the metering device is configured to transmit the meter reading data through the wireless multi-hop network.   
     
     
         13 . A communication control method performed by a wireless terminal, comprising adjusting, according to magnitude of a path cost to reach a gateway node in a wireless multi-hop network, a waiting time before joining the wireless multi-hop network after restoration of power supply to the wireless terminal. 
     
     
         14 . The communication control method according to  claim 13 , wherein the path cost includes a hop count to the gateway. 
     
     
         15 . The communication control method according to  claim 13 , wherein
 a plurality of wireless terminals in the wireless multi-hop network are divided into groups according to magnitude of a hop count to the gateway, and   the adjusting comprises adjusting the waiting time before joining the wireless multi-hop network according to magnitude of the hop count.   
     
     
         16 . The communication control method according to  claim 15 , wherein
 the adjusting the waiting time comprises adjusting a start timing of a control procedure for joining the wireless multi-hop network, and   the control procedure includes at least one of a procedure for establishing an association with a node in the wireless multi-hop network, an authentication procedure performed between the wireless terminal and the gateway, and a procedure for setting a multi-hop path between the gateway and the wireless terminal.   
     
     
         17 . The communication control method according to  claim 13 , wherein
 the wireless multi-hop network conforms to ZigBee, ZigBee PRO, or ZigBee IP,   the adjusting the waiting time comprises adjusting a start timing of a control procedure for joining the wireless multi-hop network, and   the control procedure includes at least one of (a) transmission of a Beacon Request message to an adjacent node in the wireless multi-hop network, (b) transmission of an Association Request message to the adjacent node, (c) transmission of an authentication request message to the gateway, (d) a procedure for obtaining an IP address, (e) transmission of a DODAG Information Solicitation message to the adjacent node, and (f) transmission of a DODAG Destination Advertisement Object message to the gateway.   
     
     
         18 . A non-transitory computer readable medium storing a program for causing a computer to perform a communication control method for a wireless terminal, wherein the communication control method comprises adjusting, according to magnitude of a path cost to reach a gateway node in a wireless multi-hop network, a waiting time before joining the wireless multi-hop network after restoration of power supply to the wireless terminal.